Wednesday, July 22, 2015

Endurance exercise and atrial fibrillation risk

Endurance
exercise, despite a plethora of proven health benefits, is
increasingly recognized as a potential cause of lone atrial
fibrillation. Moderate exercise reduces all-cause mortality and
protects against developing atrial fibrillation. However, more
intense exercise regimes confer modest incremental health benefits,
induce cardiac remodelling and negate some of the cardiovascular
benefits of exercise. The implications of endurance exercise and
athletic heart are becoming increasingly relevant as the popularity
of endurance exercise has increased 20-fold within a generation.

Recent
findings: An apparent dose–response relationship exists between
endurance exercise and left atrial dilatation. Repeated strenuous
endurance exercise overloads atria, resulting in stretch-induced
‘microtears’, inflammation and endocardial scarring. Although
these findings are observational in humans, similar mechanisms have
recently been confirmed in animal models suggesting causation.